1. Field of the Invention
The present invention relates to an apparatus and a method for manufacturing a wafer and more particularly to an apparatus and a method for manufacturing a wafer which can improve an efficiency in manufacturing a wafer.
2. Description of the Related Art
Conventionally, a slicing machine is used for slicing an ingot into wafers. In the slicing machine, the ingot is fixed at a feed table of the machine, which feeds an ingot in the feed direction, and after lowering an ingot to a slicing position of a blade (an inner periphery blade is generally used) against the rotating blade by means of an index mechanism of the feed table, presses the ingot against the blade and slices the ingot into sheet wafers by feeding the feed table in the slicing direction. A rotating ingot slicing machine is known, which presses a rotating ingot against a rotating blade, and this machine is characterized by shortening the time for slicing.
And, the outer periphery of the sliced wafer is formed as edge (the outer periphery of the wafer is substantially perpendicular to a slicing face of the wafer), so that chipping or a small nick easily appear, and because the wafer easily cracks due to the small shock on the outer periphery thereof, the rate of yield for manufacturing a wafer lowers. Therefore, the outer periphery of the wafer is chamfered before lapping the cutting face of the wafer with a lapping machine, so that the chipping and the cracking of the wafer can be prevented. And, conventionally, an edge grinding machine is provided between the slicing machine and the lapping machine, so that the outer periphery of the sliced wafer is chamfered. However, in the case that the lapping is performed after the chamfering as in the conventional way, since the chamfering is carried out after the chamfering portion of the outer periphery of the wafer is leveled by the rough chamfering by a grindstone #800 and the final chamfering by a grindstone #1500, the chamfering portion, which has been leveled, is like a surface ground by #800. Therefore, the chamfered portion in a good condition, which has been ground by #1500, cannot be maintained to the end of the process. As a result, there is a problem in that because there has to be a step of the rough chamfering before the lapping and a step of the final chamfering after the lapping in order to meet the requirement for the mirror grinding surface of the wafer's chamfering portion, one more step is required and the efficiency in manufacturing the wafer is lowered.